(1) Field of the Invention
This invention pertains generally to medical devices for patient monitoring, and more particularly to a system for monitoring the orientation of an individual wherein remote indications of said orientation are generated.
(2) Prior Art
Injuries sustained from falls, such as by the elderly and patients within a medical facility, can be both debilitating and costly. The social and economic costs associated with falls in the elderly have been described as “staggering” and a “public health problem of crisis proportions” (Hayes 1996). It is also a growing problem within the population as the fastest-growing segment of society are those over 65 years of age. Trends indicate that the nation's senior citizens are becoming increasingly frail, functionally dependent, and more ill than their recent counterparts (Evans 1995).
One out of every three individuals over age 65, and half of those over age 80, experience a fall each year; this percentage equates to about 10 million US residents. Falls are the leading cause of injury deaths and disabilities in this age group (Kiely 1998, NINR 1994, Rubenstein 1994). Falls account for 87% of all fractures within individuals over age 65 and are the second leading cause of spinal cord and brain injury among older adults (CDC 2000b).
Hip fractures are a common injury sustained by the elderly during such falls. The current 34 million in this population group will double in the next 40 years, and it is clear that without effective intervention strategies, the number of hip fractures will increase as the U.S. population ages (CDC 2000c). Per statistics from the Center for Disease control and Prevention, the estimated $20 billion (1994) in US direct health care costs each year due to falls continues to rise at a rate faster than the elderly population is growing. A successful reduction in fall rate would thus predict significant potential for commercial success.
The situation is especially egregious for the most frail and ill of our elderly, currently about two million of us, that require full-time care in a skilled nursing facility. Within skilled nursing facilities the residents take an average of 7.2 medications (Evans 1995), and two out of three fall at least once each year (Cooper 1997, Evans 1995). The majority of falls among the elderly within skilled nursing facilities occur in their own rooms as they attempt to get up out of the bed, without assistance, to use the lavatory at night (Alcee 2000, Capezuti 2000, Evans 1998).
In addition, numerous cases of falls occur among those with mental disorders. As many as 90% of the residents of skilled nursing facilities suffer from some form of mental disorder, including dementia (Evans 1995). An individual suffering from any form of mental confusion, whether endemic or due to the effect of medication, is subject to an increased risk of falling due to the associated impairment of judgment, lack of visual-spatial perception, loss of ability to orient themselves geographically (Rubenstein 1994), inability to understand, or impaired memory functions (Evans 1998).
In the past, patients considered to be at a high risk of falling were often restrained to their beds to prevent unassisted egress; however, it will certainly be appreciated that such treatment is contrary to the dignity of the patient. Furthermore, the use of restraints is generally impractical and it is often illegal (Health Care Reform Act of 1994). Another drawback is the inherent difficulty in attempting to accurately identify individuals that have a high likelihood of falling.
A variety of protective garments and protection devices have been studied for reducing fall-induced injuries, in particular hip fractures. In one such device, protective pads are retained proximal to the greater trochanter (upper portion of the hip bone), within a garment to displace the impact forces of a fall. Wearing these protective garments has been shown to provide a measure of protection against hip fractures, however, a large percentage of patients either refuse to wear the protective garments or become non-compliant with regard to use over time.
Recently, individuals have been monitored utilizing devices in which the individual or patient is harnessed to the monitoring device by means of wiring. These devices can be cumbersome and often restrain the movements of an individual. The benefits derived from monitoring the position and/or movement of an individual or patient have long been appreciated, and a number of monitoring devices have been considered.
The effectiveness of current devices for monitoring position or activity has been limited for several well-known reasons. Often such devices are unreliable as they rely on pendulums, mercury switches, or other forms of mechanisms that do not provide reliable detection. The majority of these devices are prone to the generation of false positives due to these inherently unreliable sensing mechanisms. Ultimately, as a result of the false alarms, the wearer or caregiver becomes conditioned to ignore the alarm, thereby negating any possible benefits that may have otherwise been derived. Unreliable sensing is particularly troublesome for devices that are not directly worn by the subject, such as pressure-activated devices, that indirectly infer subject orientation or activity.
As a group, the devices can be difficult to operate, or their operation may be suitable only for limited clinical use. A level of cognitive functioning and mental alertness is often required of those wearing the devices. This limitation can preclude the use of these devices for a substantial percentage of potential users who may be confused, disoriented, or unconscious and thus unable to activate the device.
Devices that are worn directly by a subject tend to be large, bulky, awkward, and/or uncomfortable which limits user acceptance and concomitant use. Several devices are further limited with regard to their applicability, as they may need to be worn by the human subject in a way that restrains the individual and/or comprises human dignity. Limited mobility is one particularly strong objection to many such devices which require the subject to be “attached” to the device by way of restrictive harnesses, belts, tethers, cords, cuffs, bracelets, elastic bands, or the like.
Devices requiring the aforementioned attachments are not suitable for continuous wear by an individual, and periodic disconnection is required to accommodate a number of activities, such as bathing. The restriction of movement caused by these devices is obtrusive and can noticeably interfere with sleep or daily activities. Not surprisingly, the interference that need be endured when using these devices compromises their acceptance and effectiveness. The relatively high cost of these devices is often further exacerbated by their associated methods of use which subject the devices to both damage, such as from inadvertent washing, and from theft. A further complication often arises after one of these devices becomes damaged or otherwise needs to be disposed of, because the commonly used mercury switches within the devices present a special waste disposal requirement that can be particularly challenging within a health care facility.
Attempts to solve the foregoing problems employing an assortment of electro-mechanical alarms have been largely met with failure. The actual liability associated with falls is so high that we see increasing use of these devices, apparently just to make patients and their families feel like “something” is being done, even though they are costly and ineffective. One of these problematic devices attempts to monitor the bed, or floor area near the bed, for changes in applied force. The device was found to generate false positives while being difficult to maintain and cumbersome. Independent reviews of additional devices currently on the market have concluded that no device exists which has been successful at reducing the rate of falls, and that a portion of these device types were actually associated with an increase in the incidence of falls.
The drawbacks associated with the current monitoring devices are regrettable in view of the serious nature and sheer number of injuries which are sustained from falls. Applicable subjects for attitude monitoring include a wide range of patients, and in particular those recovering from surgery or stroke, those under the influence of medications, elderly individuals in a weakened condition or suffering from dementia, or normally active individuals whose temporary condition has placed them at risk of falling. It will be appreciated that subject movement may be involuntary, such as in the case of sleepwalking, and that serious injuries may result from such movement due to a fall or the dislodgment of medical devices, which may include fluid supplies, air supplies, drainage connections, or monitoring devices. One commonly cited condition of those experiencing a fall is an altered mental state; therefore, it will be appreciated that if a device is to be successful it should not require cognitive functioning on the part of the user for activation.
Monitoring the physical activity of a subject can provide benefits within a number of applications. These include patient safety, activity studies on humans, studies on laboratory animals, compliance programs for postoperative rehabilitation or physical therapy, ensuring proper posture or sleeping position, preventing patients from becoming ambulatory without assistance, detecting subject loss of consciousness, controlling post surgical movement, or determining whether set levels of activity are being achieved.
Therefore, a need exists for a non-cumbersome device that is capable of providing reliable monitoring of subjects without the aforementioned drawbacks that are inherent in current devices. The present invention satisfies those needs, as well as others, and overcomes the deficiencies of previously developed attitude indicators and monitoring devices.